Physical protection of soil carbon in macroaggregates does not reduce the temperature dependence of soil CO2 emissions /Chevallier, Tiphaine Hmaidi, K. /Kouakoua, Ernest /Bernoux, Martial Gallali, T. /Toucet, Joële Jolivet, C. Deleporte, P. /Barthès, Bernard soil organic matter soil respiration carbon stabilization soil structure Q(10) In a warmer world, soil CO2 emissions are likely to increase. There is still much discussion about which soil organic C (SOC) pools are more sensitive to increasing temperatures. While the temperature sensitivity of C stabilized by biochemical recalcitrance or by sorption to mineral surfaces has been characterized, few studies have been carried out on the temperature sensitivityexpressed as Q(10)of C physically protected inside soil macroaggregates (0.2-2mm). It has been suggested that increasing the availability of labile SOC by exposing C through macroaggregate crushing would decrease Q(10), i.e., the temperature dependence of soil CO2 emissions. To test this hypothesis, the temperature dependence of CO2 emissions from C physically protected in macroaggregates was measured through 21-d laboratory incubations of crushed and uncrushed soils, at 18 degrees C and 28 degrees C. 199 topsoil samples, acidic or calcareous, with SOC ranging from 2 to121gkg(-1) soil were investigated. The CO2 emissions were slightly more sensible to temperature than to C deprotection: about 0.3mgCg(-1)soil (=13 mgC g(-1) SOC) and 0.2 mgC g(-1) (=12mgC g(-1) SOC) were additionally mineralized, in average, by increasing the temperature or by disrupting the soil structure, respectively. The mean Q(10) index ratio of CO2 emitted at 28 degrees C and 18 degrees C was similar for crushed and uncrushed soil samples and equaled 1.6. This was partly explained because Q(10) of macro-aggregate-protected C was 1. The results did not support the initial hypothesis of lower temperature dependence of soil CO2 emissions after macroaggregate disruption, although a slight decrease of Q(10) was noticeable after crushing for soils with high amounts of macroaggregate-protected C. Field research is now needed to confirm that soil tillage might have no effect on the temperature sensitivity of SOC stocks. 2015 text https://www.documentation.ird.fr/hor/fdi:010064900 fdi:010064900 Chevallier Tiphaine, Hmaidi K., Kouakoua Ernest, Bernoux Martial, Gallali T., Toucet Joële, Jolivet C., Deleporte P., Barthès Bernard. Physical protection of soil carbon in macroaggregates does not reduce the temperature dependence of soil CO2 emissions. 2015, 178 (4), 592-600 EN FRANCE TUNISIE